Removable muffler unit for granulator apparatus or the like

ABSTRACT

A sound muffler for attenuating sounds passing through the feed opening of an apparatus such as a granulator for plastic material or the like which generally operates at an unacceptably high noise level. A muffler unit having an essentially tubular liner of perforated material and positioning flanges is secured within the opening of a tubular feed section of the apparatus with the liner spaced from the inside walls of the feed section and sound attenuating material held by the liner and located in the space between the liner and the inside wall of the feed section. The muffler is constructed as a unit which is easily inserted in and removed from the feed section and also removably secured thereto when in use.

United States Patent Mills 1 July 22, 1975 [75} Inventor: David G. Mills, Beloit, Wis,

[73} Assignee: Beloit Corporation, Beloit, Wis.

[22] Filed: Dec. 20, 1973 21 Appl. No.: 426,456

[52] U.S. Cl 241/301; 181/33 K; 241/186 R; 24l/D1G. 28 [51] Int. Cl. B02c 23/02 [58] Field of Search 241/186 R, 100, 285 A, 241/285 B, 301, DIG. 28; 181/336, 33 K [56] References Cited UNITED STATES PATENTS 3,540,547 11/1970 Coward 181/336 3,643,880 2/1972 Peterson 241/285 B X Primary Examiner-Roy Lake Assistant Examiner-13. F. Desmond Attorney, Agent, or FirmLarson, Taylor and Hinds [57] ABSTRACT A sound muffler for attenuating sounds passing through the feed opening of an apparatus such as a granulator for plastic material or the like which generally operates at an unacceptably high noise level. A muffler unit having an essentially tubular liner of perforated material and positioning flanges is secured within the opening of a tubular feed section of the apparatus with the liner spaced from the inside walls of the feed section and sound attenuating material held by the liner and located in thespace between the liner and the inside wall of the feed section. The muffler is constructed as a unit which is easily inserted in and removed from the feed section and also removably secured thereto when in use.

11 Claims, 3 Drawing Figures PATENTED JUL 2 2 I975 SHEET 1 REMOVABLE MUFFLER UNIT FOR GRANULATOR APPARATUS OR THE LIKE BACKGROUND OF THE INVENTION This invention relates to sound attenuation, and in particular it relates to attenuating sound in the infeed section of an apparatus such as a granulator or the like which operates at a high noise level and which requires an opening, for example for feeding material thereinto, which opening tends to be a major source of noise leakage.

It has been known for some time that certain machines such as granulators operate at unacceptably high noise levels. It has also been known that much of the noise. leaks out through the raw material infeed opening. Notwithstanding such knowledge, however, until this time there have been no acceptable solutions to this noise problem, and this is true notwithstanding the recent announcements of strict governmental standards covering noise pollution.

The present practice for attenuating sound at the infeed section of an apparatus of the type described is to lineathe infeed opening which is usually tubular in shape with a suitable sound attenuating material such as expanded polyurethane foam or the like. Such foam material would be attached to the interior walls of the infeed section by any suitable means. This would normally be covered with a layer of strong perforated material such as perforated metal. When initially installed, such an arrangement operates satisfactorily. However, over. the long run such an arrangement is totally unacceptable. After avery short time, particles, some large and some in the nature of dust from the interior of the granulator fly back against the foam material and after a relatively short time they tend to fill the pores of the foam material thereby essentially reducing or eliminating its sound attenuating characteristics. It then becomes necessary to undergo the rather cumbersome task of removing this sound attenuating structure including the metal covering layers and then the foam attenuating material for cleaning the latter and on occasion replacing the same. However, this task of removing, cleaning and/or replacing the previous permanently applied sound attenuating materials tends to be rather time consuming and as a consequence thereof, the clear tendency has been to either postpone such cleaning and/or replacing procedures or forget them altogether. The ultimate result has been that the noise levels of such machines of the type described have remained at unacceptably high levels.

Thus, there exists a need for a new and improved arrangement for attenuating the sound in an apparatus of the type described.

SUMMARY OF THE INVENTION Thus, it is a purpose of the present invention to provide a new and improved sound attenuating arrangement for an apparatus of the type described.

This purpose of the invention is achieved by providing, for an apparatus of the type described, a sound attenuating muffler unit which is essentially a selfcontained unit including the perforated metal supporting structure and the sound attenuating material and which is adapted to be very easily inserted into the infeed opening of an apparatus of the type described, and then firmly but removably secured thereto and then removed therfrom without difficulty. As a result of this improvement, the task of removing the sound attenuating material for cleaning and/or replacement becomes a very easy one. I

In accordance with a preferred embodiment of the invention, the sound muffler'unit comprises an essentially tubular main section formed of a perforated metallic layer such as a sheet of metal with holes punched therein or a screen material. The term tubular is used broadly as the unit may be essentially tubular in appearance although it need not be closed on all sides; For example, the term would encompass an arrangement essentially tubular in appearance and enclosed on the top and sides but not the bottom. The tubular main section has transversely extending flanges at its ends for serving two purposes. Firstly, they position the muffler unit both axially and transversely within the infeed opening and secondly they assist in supporting sound attenuating material onto the exterior of the main section whereupon when the main section is inserted into the infeed opening the sound attenuating material partially or completely fills the space formed between the main section of the muffler unit and the interior walls of the feed section.

In accordance with another feature of the invention, the flanges remote from the feed opening would be shaped to assist primarily in positioning the unit transversely while the proximate flanges located at the end of the main section adjacent the feed opening would assist mainly in positioning the muffler unit axially, for example these flanges might engage a similar flange on the periphery of the feed opening of the apparatus. The unit would then be removably but firmly secured to the infeed opening by suitable means such as clamps or the like which might for example connect the said proximate flange to the permanent flange fixed to the infeed opening of the apparatus.

In accordance with another feature of the invention, curtains, preferably of neoprene are attached to the top of the main section of the muffler unit so as to extend downwardly to cover the opening. Such curtains will serve both to reduce noise leakage directly through the central part of this opening and to inhibit the flying back of particles which would tend to fill the pores of the foam sound attenuating material and hence reduce its sound attenuating characteristics.

Thus, it is an object of the present invention to provide a new and improved arrangement for reducing the noise level at the infeed opening of an apparatus such a granulator or the like having a feed opening.

It is another object of this invention to provide a removable sound attenuating structure for an apparatus of the type described.

It is another object of this invention to provide an arrangement for attenuating sound at the feed opening of an apparatus of the type described, in the operation of which it becomes both practical and economical to clean and/or replace the sound attenuating material so as to assure that the sound attenuating characteristics thereof are maintained at a high level at all times.

It is another object of this invention to provide a sound attenuating muffler unit as a separate cartridge adapted for attenuating sound in an apparatus of the type described.

It is still another object of this invention to provide a sound attenuating muffler arrangement, sound attenuating material on the exterior thereof and proximate and remote flanges for positioning the unit within the apparatus and for supporting vthe .sound attenuating foam material. 7

Other objects and the advantages of thepresent invention will become apparent from the detailed description to follow, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS There follows a detailed description of a preferred embodiment of the invention to be read together with the accompanying drawings which are provided for illustrative purposes only and wherein:

FIG. 1 is a central cross-sectional view through a granulator apparatus including a sound attenuating arrangement constructed in accordance with the present invention.

FIG. 2 is a composite view, the left-hand portion thereof being a cross-sectional view taken along line 2A-2A of FIG. 1 and the right-hand portion thereof being an end elevational view taken along line 28-28 of FIG. 1.

FIG. 3 is a partially exploded perspective view of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the figures, like elements are represented by like numerals throughout the several views. In the broadest sense, the present invention is adapted to attenuate sound passing through any tubular opening. For purposes of illustration, and without limiting the scope of the present invention, the present description will relate to one type of apparatus in which the sound attenuating arrangement of the present invention is particularly useful. Such an apparatus would be a granulator. Specifically, the invention has been used successfully with a granulator of the type adapted for granulating plastic material such as rejects or scrap material resulting from various plastic molding procedures such as injection molding and/or blow molding. Such a granulator is illustrated in FIG. 1 at and includes a tubular infeed section 11, a hopper 12, the actual granulator section 3 which includes a rotating blade structure 14 and a receptacle 15 for receiving the granulated material. A baffle plate 16 assists in preventing material from flying back up to the infeed section.

The sound attenuating muffler unit or cartridge is illustrated in place in FIGS. 1 and 2 and removed from the infeed section 11 in FIG. 3. This muffler unit referred to generally at 20 (see FIG. 3) includes a front or proximate flange 21 in the shape of a picture frame and having bolt holes 22 therein. The muffler unit 20 includes a liner comprising bottom 23, although in the present embodiment, since foam sound attenuating material is not placed on the exterior of the bottom 23, this bottom simply may be eliminated. The liner of the unit further includes a top and opposed sides 24 and 26. Top and sides 24-26 would be made of a perforated metal of sufficient strength and also with openings of sufficient number or of sufficient size to permit the sound to pass through the same and into the sound attenuating material on the outer surfaces of top and sides 24-26. The perforated material could also include porous materials such as sintered material or Feltmetal, which is a plurality of, screens pressed together. At the inside or remote" end of the unit 20 there are provided flanges 24a, 25a and 26a. Also shown in the figures are lower flanges 24b and 26b. These flanges may be formed as simply angled extensions of the sides or top 24-26 to which they are adjacent or alternatively separate flange elements can be attached to the respective sides and top 24-26. In any event, the unit includes proximate and remote flanges and the walls between these flanges define the main section of the muffler unit.

In a preferred arrangement, and as shown especially in FIGS. 1 and2, the flanges 24a, 25a and 260 would extend so as to just touch the inside walls of infeed section 11 thereby transversely positioning the muffler unit within this section. On the exterior of the infeed section 11 adjacent the opening thereof there is provided an external flange including a top 30, sides 31 and 32 and a bottom 33. These flanges on the section 11 include bolt holes 34 which, in the assembled states,

are aligned with bolt holes 22 of the proximate flange 21 of the muffler unit for receiving therethrough bolts 55 secured by nuts 56 (see FIGS. 1 and 2).

Thus, in the assembled state a cavity is formed between the main section of the muffler unit and the interior of the section 11. Thus space is partially orcompletely filled by a sound attenuating material such as opened cell polyurethane foam. Referring to the figures, and in particular, FIG. 3, there is shown blocks 36, 37 and 38 shaped to fit against the exterior of sidewall 24, top 25 and sidewall 26 of the muffler unit 20, respectively. These blocks of foam material may be secured in place by any convenient means. For example, the blocks 36 and 38 could simply rest on the flanges 24b and 26b respectively and the block 37 rest on top of the top 25 and one could simply hold these blocks in place as the muffler unit 20 were initially introduced into the opening of feed section 11. If greater rigidity were required, the blocks could be frictionally engaged between their adjacent proximate and remote flanges. The block 37 includes transversely extending recesses 46 and 53 for a purpose to be described hereinafter.

In use, it is desirable to provide some type of covering across the opening itself both to prevent the noise from passing through this opening and also to prevent dust or other particles from being thrown back from the granulator into the infeed section 11. For this purpose front and rear curtains 40 and are provided. These curtains and their respective supporting structures are illustrated in FIGS. 1 and 2 and a portion of the front curtain 40 is illustrated in FIG. 3. However, the rear curtain is deleted from FIG. 3 to show more clearly the slots 51 and 52 through which the curtains would pass.

The front curtain 40 comprises a length of material, perferably neoprene, which is laid over an enlongated transversely extending bar 41 and passed downwardly through a pair of slots 44 and 45 to provide the two adjacent curtains as illustrated. The curtain may be secured to the bar 41 and the top 25 by any suitable means such as bolts 42 which pass through the sheet 40, and through apertures in the rod 41 and the top 25 and which are secured by nuts 43. The curtain 50 and its supporting structure are identical to the curtain 40 and its supporting structure.

surfaces of the main section of muffler unit and secured there in the manner described above whereupon the unit 20 with the sound attenuating blocks would be slid axially into the feed opening of infeed section 11 until the flanges 21 engaged flanges -33, whereupon the bolt holes 22 would line up with the bolt holes 34 and the flanges would then be secured together by bolts and corresponding nuts 55 and 56. The sound attenuating arrangement of the present invention is now ready for use. Normally the curtains and would hang downwardly as shown in the figures. Material such as plastic scrap and reject material would be introduced through the infeed section 1 1 pushing back the curtains 40 and 50. During the granulating operation these cur tains 40 and 50 would not only assist in preventing sound leakage but they would also be helpful in preventing dust and larger particles from flying back against the perforated walls 2426. However, after a certain amount of time sufficient dirt will have passed through the walls 24-26 so as to clog the openings therein and the pores in the adjacent foam material. At this point one may simply remove the bolts and slide out the muffler unit. The foam material can then be either cleaned or replaced as required and the pores within walls 24-26 can also very easily be cleaned. The unit with cleaned or replaced foam material is then very easily reinserted back into the infeed section 11 and secured in place for further use.

Tests were conducted on a Beloit granulator, model number LB 1220, having a 15 HP. motor. The sound meter was on the A scale and the microphone was located inches high corresponding to the height of the inlet, and 3 feet from the inlet of the feed section. Polypropylene pans of approximately 15 lbs. each were fed into the granulator.

In the first test, the granulator did not have the removable muffler unit. The readings on the A scale averaged 97 decibels. In the second test, the same granulator was equiped with the removeable muffler unit of the present invention. The readings on the A scale averaged 89 decibels. This accounts for almost a 90% reduction in noise emitted from the granulator because of the exponential relationship between noise and deci bel ratings.

Although the invention has been described in considerable detail with respect to a preferred embodiment thereof, it will be apparent that the invention is capable of numerous modifications and variations apparent to those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. An apparatus for granulating plastic material or the like having a hollow elongate feed section with a feed section opening at one end to receive material to be granulated,

a liner in said feed section, said liner having at least some walls spaced from the interior surface of the feed section to form a cavity therewith,

at least a portion of the liner formed of a porous material,

a body of sound attenuating material in said cavity adjacent said porous material portion,

and positioning means for removably mounting the liner and its sound attenuating material within the feed section in such a manner as to hold the liner and its sound attenuating material at a given position when mounted in the feed section while concurrently permitting easy removal of the liner and its sound attenuating material from the feed section as a unit without substantially dismantling the remaining portion of the feed section.

2. An apparatus according to claim 1, said liner including a main section extending parallel to the axis of the feed section and spaced from the inside wall thereof and remote flanges extending from the main section transverse to the said axis, extending to the inside wall of the feed section to position the liner transversely therein at said given position, said sound attenuating material removably secured on said main section.

3. The apparatus of claim 2, including a proximate flange extending from the end of the main section of the liner closest to the feed section opening and of a larger dimension then the said feed section opening taken in the direction transverse to the said axis, whereby upon inserting the liner in the feed section opening, the proximate flange engages the feed section around the feed section opening to limit the axial movement of the liner into the feed section.

4. The apparatus of claim 3, said positioning means comprising means for removably attaching the said proximate flange to the exterior of the feed section.

5. The apparatus of claim 3, the said body of sound attenuating material being secured by frictional engagement with said proximate and remote flanges.

6. The apparatus according to claim 2, said liner defining an essentially rectangular cross-section opening therethrough and said main section forming at least essentially opposed sides and a top of the rectangular opening, the said remote flanges extending outwardly from the ends of the sides and top remote from the feed section opening transverse to the said axis to the inside wall of the feed section to position the liner therein at said given position, and including a body of sound attenuating material adjacent the external surface of each of said side and top between said sides and top and the interior wall of the feed section.

7. The appartus of claim 6, including a proximate flange comprising a rectangular frame fixed to the end of the liner closest to the feed section opening and extending beyond the periphery of the feed section opening in at least one direction to be secured to the periphery of said opening.

8. The apparatus of claim 6, including a plurality of elongated slots extending transversely across the said top of the liner, and means for securing a curtain to the top, extending downwardly through the slots, said curtain normally blocking the feed section.

9. The apparatus of claim 7, said bodies of sound attenuating material secured to the respective adjacent portions of the liner by frictional engagement with their adjacent proximate and remote flanges.

10. The apparatus of claim 1, said portions of the liner including a top portion spaced form the inside top of the feed section, including at least one sound attenuating curtain attached to the said top portion of the liner and extending downwardly therefrom to block the feed section.

11. The apparatus of claim 1, said sound attenuating material being an expanded foam material. 

1. An apparatus for granulating plastic material or the like having a hollow elongate feed section with a feed section opening at one end to receive material to be granulated, a liner in said feed section, said liner having at least some walls spaced from the interior surface of the feed section to form a cavity therewith, at least a portion of the liner formed of a porous material, a body of sound attenuating material in said cavity adjacent said porous material portion, and positioning means for removably mounting the liner and its sound attenuating material within the feed section in such a manner as to hold the liner and its sound attenuating material at a given position when mounted in the feed section while concurrently permitting easy removal of the liner and its sound attenuating material from the feed section as a unit without substantially dismantling the remaining portion of the feed section.
 2. An apparatus according to claim 1, said liner including a main section extending parallel to the axis of the feed section and spaced from the inside wall thereof and remote flanges extending from the main section transverse to the said axis, extending to the inside wall of the feed section to position the liner transversely therein at said given position, said sound attenuating material removably secured on said main section.
 3. The apparatus of claim 2, including a proximate flange extending from the end of the main section of the liner closest to the feed section opening and of a larger dimension then the said feed section opening taken in the direction transverse to the said axis, whereby upon inserting the liner in the feed section opening, the proximate flange engages the feed section around the feed section opening to limit the axial movement of the liner into the feed section.
 4. The apparatus of claim 3, said positioning means comprising means for removably attaching the said proximate flange to the exterior of the feed section.
 5. The apparatus of claim 3, the said body of sound attenuating material being secured by frictional engagement with said proximate and remote flanges.
 6. The apparatus according to claim 2, said liner defining an essentially rectangular cross-section opening therethrough and said main section forming at least essentially opposed sides and a top of the rectangular opening, the said remote flanges extending outwardly from the ends of the sides and top remote from the feed section opening transverse To the said axis to the inside wall of the feed section to position the liner therein at said given position, and including a body of sound attenuating material adjacent the external surface of each of said side and top between said sides and top and the interior wall of the feed section.
 7. The appartus of claim 6, including a proximate flange comprising a rectangular frame fixed to the end of the liner closest to the feed section opening and extending beyond the periphery of the feed section opening in at least one direction to be secured to the periphery of said opening.
 8. The apparatus of claim 6, including a plurality of elongated slots extending transversely across the said top of the liner, and means for securing a curtain to the top, extending downwardly through the slots, said curtain normally blocking the feed section.
 9. The apparatus of claim 7, said bodies of sound attenuating material secured to the respective adjacent portions of the liner by frictional engagement with their adjacent proximate and remote flanges.
 10. The apparatus of claim 1, said portions of the liner including a top portion spaced form the inside top of the feed section, including at least one sound attenuating curtain attached to the said top portion of the liner and extending downwardly therefrom to block the feed section.
 11. The apparatus of claim 1, said sound attenuating material being an expanded foam material. 